1. Field of the Invention
The present invention relates to fluorescence of the human skin and, in particular, methods and apparatus for the inducement of production of skin fluorescence by ultraviolet energy and for evaluation of skin conditions as measured by skin fluorescence. The methods and apparatus of the invention also encompass inducement of fluorescence in specific chemical compounds which are not in solution, for the purposes of measurement and evaluation.
2. Description of the Prior Art
It is known that many compounds in animal and human tissue will fluoresce as a natural phenomenon. In vivo fluorescence of tissue after treatment with photo activatable compounds such as hematoporphyrins and tetracycline has been observed. There have been reports of fluorescence without benefit of exogenous dyes in the lens of diabetic patients and in dental caries. There are no known uses, however, of tissue fluorescence for in vivo diagnostic purposes. There are no known reports of whether induction of skin fluorescence, in vivo, can be of any diagnostic value.
The skin is the body's primary defense against the environment. It is continually exposed to ultraviolet radiation (UVR) from the sun which is known to hasten the aging process (of skin). The mechanism by which UVR ages skin is unknown, and, to a large extent, measurement of this effect has been limited to in vitro, qualitative, microscopic analysis. Testing for and measurement of skin aging has been limited to skin biopsies or the creation of plaster or rubber molds of the skin in conjunction with the surface scanning of the impression. Skin biopsies: (a) are invasive and traumatic; (b) are time-consuming; and (c) provide largely qualitative results. Plaster or rubber casts are difficult to use and also provide only qualitative results.
There has also been a need for the study of pigmented skin tissue by non-invasive methods. Known techniques, such as reflectance measurements, are not sufficiently sensitive for some purposes. More sensitive techniques are needed, for example, to study changes in pigmentation over a long period of time and would be particularly useful in the study of pigmented moles, especially as they relate to the subsequent development of melanoma skin cancer.
There has additionally been a need for the study of chemical compounds such as amino acids or polypeptides, without putting them in solution so as to avoid any concern about chemical alteration of the compounds during study and testing.